Real-time safety diagnostics and fast full discharge process for battery recycling

Abstract

The present invention relates to a process for discharging a waste battery, and more specifically, to a process for discharging a waste battery by predicting the internal temperature of the waste battery based on the reciprocal value of the differential capacity of the waste battery and the discharge current, and controlling the magnitude of the discharge current according to the predicted temperature.

Description

Technology Field

[0001] The present invention relates to a discharge process for waste batteries for recycling waste batteries, and more specifically, to a process that can rapidly and safely discharge waste batteries (i.e., used batteries) to 0V before reusing or recycling them. Background Technology

[0003] Recently, the use of large-capacity lithium-ion batteries is increasing due to domestic carbon neutrality declarations and policies to promote electric vehicles.

[0004] These batteries are widely used in electric or hybrid vehicles that require large electrical capacity, and electric vehicles are receiving the most attention as a means to solve climate change problems through carbon neutrality.

[0005] However, due to the use of such a large number of batteries, the amount of waste batteries generated from electric vehicles is expected to increase rapidly in the future.

[0006] Meanwhile, if used vehicle batteries recovered from eco-friendly vehicles are disposed of immediately (e.g., resource recovery), enormous disposal costs will be incurred annually starting from 2024, and disposal costs are predicted to increase explosively from 2031 onwards.

[0007] To partially resolve these issues, spent automotive batteries must be recycled for other applications. This recycling process requires crushing the batteries and extracting high-purity black powder through metallurgy. However, crushing batteries while they still contain residual energy can lead to ignition or explosion; therefore, recycling spent automotive batteries without any guarantees poses significant technical and social risks. Consequently, a pretreatment process is essential to reduce the remaining energy of the batteries to zero before crushing.

[0008] However, for the recycling or reuse of waste batteries, there are issues such as the internal temperature of the waste battery rising rapidly during the discharge process, even when the remaining energy, or the charged power, is lowered below a certain SOC or completely discharged to 0V; therefore, it is necessary to develop a discharge process to address this. Prior art literature

[0010] Republic of Korea Published Patent 10-2019-0018340 (2019.2.22) The problem to be solved

[0011] The first problem that the present invention aims to solve is to provide a battery discharge process that safely and completely discharges the pre-charged power of a waste battery in real time prior to the reuse or recycling of the waste battery.

[0012] The second problem that the present invention aims to solve is to provide a discharge process capable of predicting the internal temperature of a waste battery in real time by utilizing diagnostic factors such as resistance, power, and energy that can be obtained in real time.

[0013] The third problem that the present invention aims to solve is to provide a discharge process capable of calculating the largest discharge current within a safe temperature range after predicting the internal temperature of a waste battery.

[0014] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. means of solving the problem

[0016] A process for discharging waste batteries according to an embodiment of the present invention for achieving the above-mentioned problem is,

[0017] (S100) A step of discharging the waste battery with a first discharge current through a connection terminal connected to the power terminal of the waste battery;

[0018] (S200) A step of monitoring dV / dQ, which is the inverse of the differential capacity of the waste battery, according to time or voltage;

[0019] (S300) A step of predicting the temperature inside the waste battery based on dV / dQ, which is the reciprocal of the differential capacity of the waste battery, and the first discharge current; and

[0020] (S400) Based on the predicted temperature exceeding a first threshold, the method may include a step of controlling the discharge to a second discharge current lower than the first discharge current through a connection terminal connected to the power terminal of the waste battery.

[0021] In one embodiment of the present invention, the step (S300) is,

[0022] A step of obtaining a power (P) value through dV / dQ, which is the reciprocal of the differential capacity of the waste battery, and the first discharge current; and

[0023] The method may include a step of predicting the temperature inside the waste battery based on at least one of the initial temperature of the waste battery, the weight of the waste battery, the power (P) value, and the energy (E) value.

[0024] In one embodiment of the present invention, based on the fact that dV / dQ, which is the reciprocal of the differential capacity of the waste battery, exceeds a second threshold value, the waste battery may be controlled to discharge at a second discharge current lower than the first discharge current through a connection terminal connected to the power terminal of the waste battery.

[0025] A process for discharging waste batteries according to an embodiment of the present invention for achieving the above-mentioned problem is,

[0026] (S500) Based on the fact that the predicted temperature is below the first threshold value, the method may further include a step of controlling the discharge to a third discharge current higher than the first discharge current through a connection terminal connected to the power terminal of the waste battery.

[0027] In one embodiment of the present invention, the predicted temperature calculated based on at least one of the third discharge current, the power (P) value and the energy (E) value of the waste battery may be less than the first threshold value.

[0028] A process for discharging waste batteries according to an embodiment of the present invention for achieving the above-mentioned problem is,

[0029] (S600) When the voltage of the waste battery reaches a specific voltage while discharging the waste battery, the method may further include the step of applying a constant voltage.

[0030] A process for discharging waste batteries according to an embodiment of the present invention for achieving the above-mentioned problem is,

[0031] (S700) The above constant voltage may be applied and, when a specific time has elapsed or the cut-off current resulting from the application of the above constant voltage reaches a third threshold, the step of stopping the discharge of the waste battery may be further included.

[0032] A process for discharging waste batteries according to an embodiment of the present invention for achieving the above-mentioned problem is,

[0033] (S800) To prevent voltage rebound of the waste battery, the method may further include the step of short-circuiting the battery.

[0034] The means for solving the above problem do not enumerate all the features of the present invention. Various features of the present invention and the resulting advantages and effects can be understood in more detail by referring to the specific embodiments below. Effects of the invention

[0035] By various embodiments of the present invention, a waste battery complete discharge process capable of safely and rapidly completely discharging a waste battery in real time can be provided.

[0036] Through various embodiments of the present invention, it can be utilized as a basic facility for the storage, transportation, and reuse of waste batteries, and it is expected that safety in the battery reuse and recycling industry can be improved.

[0037] By various embodiments of the present invention, it is possible to prevent a situation in which a fire occurs due to heat generation caused by resistance in the irreversible section during the process of completely discharging a waste battery.

[0038] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description below. Brief explanation of the drawing

[0040] Figure 1 is a block diagram illustrating the configuration of a waste battery discharge device. Figure 2 is a flowchart illustrating the discharge process based on the temperature prediction inside the waste battery. Figure 3 shows that when the discharge of the waste battery is performed, the actual internal temperature of the waste battery matches the predicted temperature (calculated temperature) of the battery derived through Equation 5 of the present invention. Figure 4 is a graph showing a conceptual diagram of the internal temperature change of a waste battery (Figure 4c) considering the heat generation factor of the waste battery (Figure 4a) and the heat dissipation factor of the waste battery (Figure 4b). Figure 5 is a graph showing the change in dV / dQ of the waste battery over time. Figure 6 is a graph showing the temperature change of the waste battery over time. Figure 7 is a graph showing the actual internal temperature change of a waste battery over time. Figure 8 is a graph showing the changes in internal temperature, current, voltage, and capacity of a waste battery over time. Specific details for implementing the invention

[0041] The principles of a preferred embodiment of the present invention will be explained in detail below with reference to the attached drawings and description. However, the drawings and descriptions below relate to preferred embodiments among various methods for effectively explaining the features of the present invention, and the present invention is not limited to the drawings and descriptions below.

[0042] Meanwhile, terms such as "first" or "second" may be used to describe various components, but these terms should be interpreted solely for the purpose of distinguishing one component from another. For example, a first component may be named a second component, and similarly, a second component may be named a first component.

[0043] The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, terms such as "comprising" or "having" are intended to specify the existence of the described features, numbers, steps, actions, components, parts, or combinations thereof, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0044] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this specification.

[0045] Hereinafter, a method for discharging a waste battery within a safe temperature range by predicting the temperature inside the waste battery according to an embodiment of the present invention will be described with reference to the attached drawings.

[0046] In describing the present invention, the term "waste battery" may collectively refer to waste batteries that have been used and recovered for various reasons. For example, waste batteries may include, but are not limited to, vehicle waste batteries that have been used in eco-friendly vehicles (e.g., electric vehicles, hydrogen vehicles, etc.) and recovered for various reasons (e.g., inspection, repair, expiration of service life, accident, scrapping, etc.).

[0047] Meanwhile, resistance may increase during the irreversible phase of a spent battery's complete discharge, which can lead to thermal runaway or fire due to high heat generation. Although the internal temperature of the spent battery can be measured using IR sensors and / or thermocouples, accurate temperature measurement is impossible due to the plastic composites used as insulation, and there is a problem in that the risk of thermal runaway during discharge cannot be detected due to the high current.

[0048] In order to solve the aforementioned problems, a waste battery discharge process according to one embodiment of the present invention is described below with reference to the attached drawings.

[0049] FIG. 1 is a block diagram of a discharge system according to one embodiment of the present invention.

[0050] Referring to FIG. 1, a discharge system (100) according to an embodiment of the present invention may include a charging / discharging unit (110) that adjusts the current through a terminal (140) connected to a waste battery (200), a voltage measuring unit (120), and a memory unit (130).

[0051] The charging / discharging unit (110) can charge or discharge the waste battery (200) by providing a charging current or a discharging current to the waste battery (200) through the connection terminal (140). Additionally, the charging / discharging unit (110) can control the magnitude of the charging current or discharging current provided to the waste battery (200) according to the amount of capacity change according to the voltage of the waste battery (200).

[0052] The voltage measuring unit (120) can measure and monitor the voltage within the waste battery (200) through the current flowing through the connection terminal (140). The voltage measured by the voltage measuring unit (120) can be used to monitor the change in capacity according to the voltage of the waste battery (200).

[0053] Meanwhile, the voltage measuring unit (120) may include a profile generating unit (121). The profile generating unit (121) may be configured to obtain battery information including voltage (V) and capacity (Q) for a battery cell (B).

[0054] The profile generation unit (121) may be configured to generate a battery profile representing the corresponding relationship between the voltage and the capacity based on the acquired battery information.

[0055] Specifically, the profile generation unit (121) can generate a battery profile by mapping corresponding voltages and capacities among the acquired battery information. Additionally, the generated battery profile can be configured to convert into a differential capacity profile that represents the corresponding relationship between the voltage and the differential capacity with respect to the voltage. Differential capacity is a value obtained by differentiating the capacity with respect to the voltage for corresponding voltages and capacities, and specific details will be described later.

[0056] The memory unit (130) can store various data obtained through the charging / discharging unit (110) and the voltage measuring unit (120). The memory unit (130) can be electrically connected to the charging / discharging unit (110) and the voltage measuring unit (120). However, this is merely one embodiment, and the memory unit (130) can be wirelessly connected to the charging / discharging unit (110) and the voltage measuring unit (120).

[0057] The connection terminal of the connection part (140) is electrically connected to the power terminal of the waste battery (200), and the connection part (140) provides an electrical circuit for measuring the voltage value or current value of the waste battery (200) or for charging or discharging the waste battery (200) through the connection terminal.

[0058] FIG. 2 is a flowchart illustrating a discharge process based on temperature prediction inside a waste battery according to an embodiment of the present invention. Referring to FIG. 2, the present invention:

[0059] (S100) A step of discharging the waste battery with a first discharge current through a connection terminal connected to the power terminal of the waste battery;

[0060] (S200) A step of monitoring dV / dQ, which is the inverse of the differential capacity of the waste battery, according to time or voltage;

[0061] (300) A step of predicting the temperature inside the waste battery based on dV / dQ, which is the reciprocal of the differential capacity of the waste battery, and the first discharge current;

[0062] (S400) A step of controlling the discharge to a second discharge current lower than the first discharge current through a connection terminal connected to the power terminal of the waste battery based on the predicted temperature exceeding the first threshold;

[0063] (S500) A step of controlling the discharge to a third discharge current higher than the first discharge current through a connection terminal connected to the power terminal of the waste battery, based on the fact that the predicted temperature is below the first threshold value;

[0064] (S600) A step of applying a constant voltage when the voltage of the waste battery reaches a specific voltage while discharging the waste battery; and

[0065] (S700) A step of stopping the discharge of the waste battery when the above constant voltage is applied and a specific time has elapsed or when the cut-off current resulting from the application of the above constant voltage reaches a third threshold value;

[0066] (S800) A step of short-circuiting the battery to prevent voltage rebound of the waste battery.

[0067] A waste battery discharge process including can be provided.

[0068] The configuration of the present invention will be described in more detail below.

[0069] 1. (S100) A step of discharging the waste battery with a first discharge current through a connection terminal connected to the power terminal of the waste battery.

[0070] Step (S100) is a step of discharging the waste battery through the connection terminals of the waste battery. In the present invention, Step (S100) may vary depending on the characteristics of the waste battery, for example, the type of the components (electrode material) constituting the waste battery.

[0071] Since used vehicle batteries recovered from eco-friendly vehicles are collected due to various reasons, they may not be recovered in a state where the stored energy has been completely discharged.

[0072] Because charged batteries pose a risk of fire or explosion in the event of external shock or stimulation due to the energy stored inside, it is very dangerous to recycle them as is without any guarantee.

[0073] Accordingly, the above step (S100) is a step of discharging the waste battery through a terminal connected to the waste battery in order to lower the energy level charged in the waste battery.

[0074] Meanwhile, in the waste battery discharge process according to the present invention, a step of recovering waste batteries from various devices (e.g., eco-friendly vehicles, etc.), separating the battery manufacturer's BMS and vehicle case (optional) from the waste batteries, and preparing a battery module including N battery cells may be performed first.

[0075] Additionally, in a discharge process for a waste battery according to one embodiment of the present invention, the steps of preparing the waste battery, specifying the specifications of the waste battery, and inspecting the electrical flow of the waste battery may be performed first.

[0076] Specifically, the step of selecting the specifications of the waste battery may include a step of determining the type of waste battery by considering the components constituting the waste battery (e.g., positive electrode material, negative electrode material, electrolyte, etc.).

[0077] Since the capacity-voltage curve, which indicates the discharge characteristics of a battery, is determined by the positive and negative electrode materials, the specifications of the waste battery must always be considered in order to set specific conditions of the discharge process, such as the discharge voltage and current described later.

[0078] Additionally, the electrical flow inspection may include an insulation resistance measurement step, a voltage measurement step, and an EIS (Electrochemical Impedance Spectroscopy) measurement step.

[0079] In this way, by performing an electrical flow inspection before discharging the waste battery, the electrical safety of the waste battery to be discharged can be evaluated, and the State of Charge (SOC) and State of Health (SOH) of the waste battery can be diagnosed. At this time, the SOC and SOH measured during the electrical flow inspection are applied to set the conditions for the subsequent discharge process.

[0080] In describing the present invention, (discharge) voltage refers to the potential difference between the positive and negative electrodes, a value measured based on a single cell, and in battery modules or packs, the voltage reference may vary depending on the battery configuration.

[0081] For example, in a module or pack where N (N≥2) single cells are connected in series, the discharge voltage "single cell voltage * N" can be the (discharge) voltage.

[0082] In the discharge process of a waste battery according to the present invention, the discharge voltage considering the positive and negative materials constituting the waste battery may be -1.5 V to 3.0 V, preferably -1.0 V to 2.5 V, more preferably 0 V to 1.0 V based on a single cell.

[0083] Meanwhile, in the discharge process of a waste battery according to the present invention, step (S100) may involve discharging the waste battery at a specific discharge voltage with a first current magnitude through a connection terminal.

[0084] Here, the first current magnitude may be a constant current of 0.5C (C-rate) to 5.0C (C-rate), preferably 0.5C (C-rate) to 3.0C (C-rate).

[0085] Here, C-rate is an abbreviation for current rate and refers to a battery-related characteristic indicating the charge / discharge rate of current according to battery capacity; the actual unit is [ / h], but the unit [C] is generally used.

[0086] For example, if the battery capacity (amount of current that can be used for 1 hour) is 1000 mAh and the charge / discharge current is 1 A, the C-rate becomes 1 C * 1 A / 1000 mAh = 1 [ / h].

[0088] 2. (S200) A step of monitoring dV / dQ, which is the inverse of the differential capacity of the waste battery, according to time or voltage;

[0089] In the discharge process of a waste battery according to the present invention, step (S200) is a step of monitoring the differential capacity of the waste battery.

[0090] Specifically, the above step (S200) is a step of monitoring the differential capacity while the waste battery is discharged with a first discharge current through the connection terminal.

[0091] Here, differential capacity is the value obtained by differentiating the capacity with respect to the voltage with respect to the corresponding voltage and capacity of the battery, and can be expressed as "dQ / dV", where the unit of differential capacity can be [mAh / V] or [Ah / V].

[0092] In another embodiment of the present invention, the differential capacity may be "dV / dQ," which is the reciprocal of "dQ / dV," and the unit of the differential capacity may be [V / mAh] or [V / Ah].

[0093] During the discharge process of the waste battery, the profile generation unit (121) of the discharge system (100) continuously calculates the dQ and dV values ​​of the battery based on the battery voltage information received from the voltage measurement unit (120) and calculates "dQ / dV". However, if the calculation cycle is very short depending on the discharge condition of the waste battery, and the dV value approaches 0, the differential capacity "dQ / dV" may approach infinity, and in this case, a problem may occur in the calculation process of the differential capacity.

[0094] Therefore, depending on the purpose of solar / discharge of the waste battery, the reciprocal "dV / dQ" may be used as the differential capacity instead of "dQ / dV". In the present invention, both "dQ / dV" and "dV / dQ" are defined as differential capacity; however, in cases where "dQ / dV" is defined as differential capacity, "dV / dQ" may be named as the reciprocal of differential capacity to distinguish the terms.

[0095] A profile generation unit (121) of a discharge system (100) according to one embodiment of the present invention can generate a differential capacity profile of a battery based on battery voltage information received from a voltage measurement unit (120) and monitor it.

[0096] Here, the differential capacity monitoring period may be 100 ms to 5 min, but this is merely one example and can be set to various values.

[0097] 3. (S300) A step of predicting the temperature inside the waste battery based on dV / dQ, which is the reciprocal of the differential capacity of the waste battery, and the first discharge current.

[0098] In the discharge process of a waste battery according to the present invention, the step (S300) is a step of predicting the temperature inside the waste battery using dV / dQ, which is the reciprocal of the differential capacity monitored in the step (S200), and a first discharge current.

[0099] In one example of the present invention, the step (S300) comprises a step (S310) of obtaining an energy (E) value (≈heat generation) generated in the battery through dV / dQ, which is the reciprocal of the differential capacity of the waste battery, and a first discharge current, and an initial temperature (T) of the waste battery. i It may include a step (S320) of predicting the temperature inside the waste battery based on at least one of the weight, power (P) value, energy (E) value, first discharge current and discharge voltage.

[0100] The values ​​of power (P) and energy (E) (≈heat generation) can be derived through Equation 1 and Equation 2, respectively. Here, V represents the discharge voltage, I represents the discharge current, R represents the resistance, and t represents time (s).

[0101] [Mathematical Formula 1]

[0102]

[0103] [Mathematical Formula 2]

[0104]

[0105] The reciprocal of the differential capacity of the waste battery, dV / dQ, can correspond to the value of resistance (R) according to Ohm's law (i.e., dV / dQ ≈ R). Therefore, power (P) and energy (E) can be derived through the following mathematical equations 3 and 4.

[0106] [Mathematical Formula 3]

[0107]

[0108] [Mathematical Formula 4]

[0109]

[0110] The discharge system (100) can obtain a power (P) value through dV / dQ, which is the reciprocal of the differential capacity of the waste battery, and a first discharge current.

[0111] Accordingly, the discharge system (100) can derive the amount of heat generated in the battery by integrating the discharge current with respect to time with respect to the reciprocal of the differential capacity obtained in advance. That is, the amount of heat generated in the battery can be expressed as a function of the differential capacity.

[0112] In the present invention, the amount of heat generated is not calculated using the voltage (V) applied to the battery, but rather using differential capacity to calculate the amount of heat generated by the battery, because the voltage (V) is not an internal factor of the battery and therefore has limitations in accurately predicting the amount of heat generated inside the battery.

[0113] Meanwhile, the discharge process of a waste battery according to the present invention may consider the mass factor of the battery when obtaining the energy (E) value generated from the battery. The amount of heat generated by the battery calculated through Equation 4 above may increase as more batteries are used (e.g., a battery module with connected unit batteries). Therefore, to correct this, the value obtained by dividing the energy (E) value of Equation 4 by the mass factor of the battery can be used as the amount of heat generated from the battery (Equation 5 below).

[0114] [Mathematical Formula 5]

[0115]

[0116] In this case, the mass factor of the battery may be defined differently depending on the use of the battery. For example, the mass factor m of the battery may be the cell mass of the battery, or the mass of the pack, or the mass of the module, or the total mass of the elements capable of dissipating heat within the battery, and most preferably, the cell mass is used.

[0117] That is, the discharge process of the waste battery according to the present invention is not limited to a specific mass factor, and an appropriate mass factor can be selected depending on the usage of the waste battery.

[0118] Figure 3 shows the actual internal temperature of the battery and the predicted temperature (calculated temperature) of the battery derived through Equation 5 when the discharge of the waste battery is performed. As can be seen in Figure 3, it can be confirmed that the actual internal temperature of the waste battery and the predicted temperature of the waste battery derived through Equation 5 are almost identical.

[0119] Meanwhile, the internal temperature of the battery may follow a downward curve due to the heat dissipation generated during the discharge of the waste battery (Fig. 7). In this case, the internal temperature of the battery can be derived through Equation 6, which takes into account the heat dissipation factor (value of the internal temperature decrease).

[0120] [Mathematical Formula 6]

[0121]

[0122] The formula including the constant c1 in the above mathematical formula 6 represents the exothermic factor, and is a formula including temperature change and a constant c2. represents the heat dissipation factor.

[0123] The above heat generation and heat dissipation factors are values ​​derived from the general formula Q=C△T related to thermal capacity, and the temperature drop of the battery can be predicted relatively accurately by calculating the amount of heat dissipated according to the temperature change.

[0124] Here, can refer to the value obtained by subtracting the initial temperature (Ti) of the waste battery from the predicted internal temperature (Tf) of the waste battery derived at a specific point in time. In other words, the heat dissipation factor is The value obtained by integrating over time can be derived by dividing the value by the weight (m) of the waste battery and multiplying by a negative constant (c2) (see Fig. 4), and the greater the temperature change, the greater the temperature drop of the battery.

[0125] As a result, the discharge system (100) can accurately monitor the actual temperature change of the battery during the discharge process through data (e.g., heat dissipation factor) corresponding to the weight and initial temperature of the waste battery, the amount of heat calculated through differential capacity, and the internal temperature of the battery.

[0126] (S400) A step of controlling the discharge to a second discharge current lower than the first discharge current through a connection terminal connected to the power terminal of the waste battery based on the above predicted temperature exceeding the first threshold value.

[0127] In the discharge process of a waste battery according to the present invention, step (S400) is a step of lowering the discharge current value applied to discharge the waste battery when it is identified that the temperature value predicted through step (S300) exceeds a first threshold value.

[0128] In one embodiment of the present invention, the first threshold value may be 40 to 50 degrees, and preferably 45 to 50 degrees.

[0129] At this time, in order to determine whether to set the discharge current to a low value, it may be monitored whether the predicted temperature is maintained for at least 30 seconds, preferably at least 1 minute, after it is identified that the temperature has exceeded the first threshold value.

[0130] For example, if the predicted temperature is identified as exceeding a first threshold and is maintained for more than 1 minute, the discharge current value of the waste battery can be controlled from a first discharge current to a second discharge current.

[0131] As an example of the present invention, referring to FIGS. 5 and 6, the value of dV / dQ, which is the inverse of the differential capacity of the waste battery, may increase rapidly during a time interval of about 2,000 sec to 2,500 sec. Also, referring to FIG. 6, when the discharge current value is 2.0C or 1.0C, the temperature inside the waste battery may increase rapidly as the value of dV / dQ, which is the inverse of the differential capacity of the waste battery, increases rapidly during the corresponding time interval.

[0132] At this time, the discharge system (100) can lower the temperature inside the waste battery by lowering the discharge current value. For example, the discharge system (100) can lower the temperature inside the waste battery by lowering the discharge current value from 2.0C or 1.0C to 0.3C or 0.5C. Through this, the discharge system (100) can perform a discharge operation by continuously applying a discharge current within a safe temperature range.

[0133] FIG. 8 is a graph showing the changes in internal temperature, current, voltage, and capacity of a battery over time when the operation described above is applied, as an embodiment of the present invention.

[0134] Discharge operation on the waste battery can be performed with a discharge current of about 100A from 0 sec to 2,000 sec. During the time interval from 2,000 sec to 2,500 sec, the temperature inside the waste battery may increase rapidly as the value of dV / dQ, which is the inverse of the differential capacity of the waste battery, increases rapidly.

[0135] As described above, the discharge system (100) can predict the temperature inside the waste battery by monitoring the dV / dQ value, which is the reciprocal of the differential capacity of the waste battery. The discharge system (100) can reduce the discharge current value to about 25A after identifying that the predicted temperature value inside the waste battery exceeds a first threshold value in the time interval of 2,000 sec to 2,500 sec. Accordingly, the temperature inside the waste battery can gradually decrease.

[0136] As another example of the present invention, based on the fact that dV / dQ, which is the reciprocal of the differential capacity of the waste battery, exceeds a second threshold value, the waste battery can be controlled to discharge at a second discharge current lower than the first discharge current through a connection terminal connected to the power terminal of the waste battery.

[0137] That is, if the discharge system (100) identifies that dV / dQ, which is the inverse of the differential capacity monitored through step (S200), exceeds a second threshold value, it can control the discharge to a second discharge current lower than the first discharge current through a connection terminal connected to the power terminal of the waste battery.

[0138] Here, the second threshold value may be 10 to 20, and preferably set to 15 to 18.

[0140] (S500) Based on the predicted temperature being below a first threshold value, control to discharge at a third discharge current higher than the first discharge current through a connection terminal connected to the power terminal of the waste battery.

[0141] In the discharge process of a waste battery according to the present invention, step (S500) is a step of increasing the discharge speed by controlling the discharge to a third discharge current higher than the first discharge current through a connection terminal connected to the power terminal of the waste battery when the predicted temperature does not exceed a first threshold value.

[0142] At this time, the discharge system (100) can adjust the third discharge current value so that the predicted temperature value calculated based on at least one of the third discharge current, power value, and energy (E) value does not exceed the first threshold value. That is, the discharge system (100) can perform the discharge procedure with the largest discharge current within a safe temperature range.

[0143] For example, the discharge system (100) can increase the discharge current by a certain unit value. That is, if the predicted temperature does not exceed a first threshold value, the discharge system (100) can increase the discharge current by a certain unit value and then predict the temperature inside the waste battery again. If the predicted temperature inside the waste battery does not exceed the first threshold value after increasing the discharge current value from the first discharge current to the third discharge current, the discharge system (100) can increase the discharge current by a certain unit value again.

[0145] (S600) A step of applying a constant voltage when the voltage of the waste battery reaches a specific voltage while discharging the waste battery.

[0146] In the discharge process of a waste battery according to the present invention, the step (S600) is a step of applying a constant voltage (CV) to the waste battery when the voltage of the waste battery reaches a specific voltage (e.g., 0V).

[0147] Specifically, by applying a constant voltage in the above step (S600) (i.e., by entering CV mode and performing a discharge operation on the waste battery), over-discharge of the waste battery can be induced.

[0148] Meanwhile, in the discharge process of the waste battery according to the present invention, the constant voltage applied in step (S600) may be a voltage where the difference in energy levels between the positive and negative electrodes is close to zero, that is, a voltage close to 0 V.

[0149] In this way, by desorbing residual lithium ions from the negative electrode, the spent battery can be completely discharged, and the energy level remaining in the spent battery can be minimized.

[0150] In the discharge process of a waste battery according to the present invention, the constant voltage may be 0V to 0.5V based on a single cell, preferably 0V to 0.1V.

[0151] In the discharge process of a waste battery according to the present invention, the application of a constant voltage in step (S600) may be applied until a cut-off current magnitude of 0.005 to 0.5 C, preferably 0.01 C to 0.1 C, is measured.

[0152] Here, the cut-off current refers to the current generated by the application of a constant voltage, and as the constant voltage continues to be applied, it approaches over-discharge, so the magnitude of the generated current gradually decreases. At this time, when the magnitude of the cut-off current reaches 0.005C to 0.5C, preferably 0.01C to 0.1C, the applied constant voltage is stopped and the discharge is stopped.

[0154] (S700) A step of stopping the discharge of the waste battery when the above constant voltage is applied and a specific time has elapsed or when the cut-off current resulting from the application of the above constant voltage reaches a third threshold value.

[0155] In the discharge process of a waste battery according to the present invention, the step (S700) is a step of applying a constant voltage and stopping the discharge of the waste battery when a specific time has elapsed or when the cut-off current resulting from the application of the constant voltage reaches a third threshold value.

[0156] Here, the cut-off current refers to the current generated by the application of a constant voltage, and as the constant voltage continues to be applied, it approaches complete discharge, so the magnitude of the generated current may gradually decrease. At this time, when the magnitude of the cut-off current reaches within 0.005C to 0.5C, preferably 0.01C to 0.1C, the applied constant voltage may be stopped and the discharge may be discontinued.

[0158] (S800) A step of short-circuiting the battery to prevent voltage rebound of the waste battery.

[0159] In the discharge process of a waste battery according to the present invention, the step (S800) is a step of artificially connecting the positive and negative electrodes of the waste battery to form a short circuit, thereby eliminating residual energy within the waste battery. In general batteries, the voltage may rise again even after discharge is completed due to the voltage recovery characteristics of the battery itself. To prevent this, the positive and negative electrodes of the waste battery are connected to form a short circuit, thereby reducing the possibility of voltage rising again, sparks, and fire.

[0160] Meanwhile, the embodiments of the present invention described above can be written as a program that can be executed on a computer, and the written program can be stored on a medium.

[0161] A medium may continuously store a program executable by a computer, or temporarily store it for execution or download. Additionally, the medium may be various recording or storage means in the form of a single or multiple combined hardware components; it is not limited to a medium directly connected to a computer system, but may also exist distributed across a network.

[0162] Examples of media include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs and DVDs; magneto-optical media such as floptical disks; and media configured to store program instructions, including ROM, RAM, and flash memory. Additionally, other examples of media include recording media or storage media managed by app stores that distribute applications or sites and servers that supply or distribute various other software.

[0163] For the time being, the embodiments described in this invention and the accompanying drawings are merely illustrative of a part of the technical concept included in this invention. Accordingly, since the embodiments disclosed in this specification are intended to explain, not limit, the technical concept of this invention, it is obvious that the scope of the technical concept of this invention is not limited by these embodiments.

[0164] All variations and specific embodiments that can be easily deduced by a person skilled in the art within the scope of the technical ideas contained in the specification and drawings of the present invention should be interpreted as being included within the scope of the rights of the present invention. Explanation of the symbols

[0165] 100: Battery Discharge System 110: Charging / Discharging Unit 111: Charge / Discharge Current Control Unit 120: Voltage measuring section 130: Memory section 140: Connection terminal 200: Waste battery

Claims

Claim 1 A waste battery discharge process comprising: (S100) discharging the waste battery at a first discharge current through a connection terminal connected to a power terminal of the waste battery; (S200) monitoring dV / dQ, which is the inverse of the differential capacity of the waste battery according to time or voltage; (S300) predicting the internal temperature of the waste battery based on dV / dQ, which is the inverse of the differential capacity of the waste battery, and the first discharge current; (S400) controlling the discharge to a second discharge current lower than the first discharge current through a connection terminal connected to a power terminal of the waste battery based on the predicted temperature exceeding a first threshold; and (S500) controlling the discharge to a third discharge current higher than the first discharge current through a connection terminal connected to a power terminal of the waste battery based on the predicted temperature being below the first threshold. Claim 2 A waste battery discharge process according to claim 1, wherein the step (S300) comprises: a step of obtaining a power (P) value through dV / dQ, which is the reciprocal of the differential capacity of the waste battery, and the first discharge current; and a step of predicting the temperature inside the waste battery based on at least one of the initial temperature of the waste battery, the weight of the waste battery, the power (P) value, and the energy (E) value. Claim 3 A waste battery discharge process according to claim 2, further comprising the step of controlling the waste battery to discharge at a second discharge current lower than the first discharge current through a connection terminal connected to the power terminal of the waste battery, based on the fact that dV / dQ, which is the reciprocal of the differential capacity of the waste battery, exceeds a second threshold value. Claim 4 A waste battery discharge process according to claim 1, further comprising the step of (S500) controlling to discharge at a third discharge current higher than the first discharge current through a connection terminal connected to the power terminal of the waste battery based on the predicted temperature being lower than the first threshold value. Claim 5 In claim 1, the above step (S500) comprises the step of determining the third discharge current such that the predicted temperature calculated based on at least one of the third discharge current, the power (P) value and the energy (E) value of the waste battery is less than the first threshold value; a waste battery discharge process. Claim 6 In claim 4, (S600) a waste battery discharge process further comprising the step of applying a constant voltage when the voltage of the waste battery reaches a specific voltage while discharging the waste battery. Claim 7 A waste battery discharge process according to claim 6, further comprising the step of stopping the discharge of the waste battery when the constant voltage is applied and a specific time elapses or when the cut-off current resulting from the application of the constant voltage reaches a third threshold value. Claim 8 A waste battery discharge process according to claim 1, further comprising the step of controlling the waste battery to discharge at a discharge current higher than the third discharge current through a connection terminal connected to the power terminal of the waste battery, based on the fact that the predicted temperature is below the first threshold value even after performing the step (S500).

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